How to add an object from another scene?
If the scenes are in the same .blend file:


Be in the destination scene
From the Outliner, make sure you see all scenes
In the Outliner, expand the scene with the object you want and drill down to that object
Left-click and drag the icon for that object into your 3D View
Boom... you've copied it over


If the scenes are in different files


File > Append (or Shift+F1)
From Blender's File Browser, go to the .blend file you want to pull from
Left-click the .blend file and go to the Object sub-directory within it
Choose the object you want to get (you did give it a sensible name, right?)
Click the "Link/Append from Library" button in the upper right corner